Aluminum chlorhydroxide has been used for a number of years as the active ingredient in antiperspirant compositions. This has been available commercially as a 50% aqueous solution and has been marketed under the trademark CHLORHYDROL. The formula of aluminum chlorhydroxide has been generally given by the structure Al.sub.2 (OH).sub.5 Cl. However, it has long been realized that at best this structure represented the empirical formula and that aluminum chlorhydroxide is a very complicated material.
More recently it has been discovered that in fact aluminum chlorhydroxide is at least a mixture of molecular species representing different degrees of polymerization of aluminum chlorhydroxide that may correspond to the empirical formula Al.sub.2 (OH).sub.5 Cl. Moreover, it has been found that the various molecular species do not have the same degree of effectiveness as antiperspirant agents but that as a matter of fact one species is superior to the others in this activity. For reasons that will become more apparent later this species or fraction is identified herein as the K.sub.d =0.4 fraction. The present invention is concerned with a process for preparing an aluminum chlorhydroxide product high in the K.sub.d =0.4 fraction i.e. of the order up to about 85% by weight of the total aluminum chlorhydroxide product.